The present invention relates to a working vehicle having a pair of opposite wheels movable up and down with each other in opposed relation, a pair of hydraulic cylinders extensible or contractable in opposed relation to each other by the up-and-down movement of the wheels and interconnected by a closed piping channel, a stop valve mounted on the closed piping channel and brakes for braking the vehicle during running and also for parking the vehicle, the vehicle thus being adapted to travel on a rough ground with stability by absorbing the jerky movement of the vehicle body due to the irregularities on the ground surface.
While vehicles of this type are stopped and operated for working in a fixed position, the vehicle body is liable to jolt when subjected to the working reaction of the working implement and therefore fails to ensure a smooth operation with stability. Accordingly it is necessary to restrain the wheels against an up-and-down jerky movement. To assure this effectively, the wheels are usually adapted to be so restrained by a brake actuating procedure. Such an operatively associated arrangement nevertheless involves the problem that when the brake is operated for a speed reduction during running as well as for stopping or parking, the wheels are restrained from moving up and down, consequently reducing the stability of the vehicle during travel.